Tube drawing apparatus



Aug 24, 1943.

R. E. SLATER TUBE DRAWING APFARATUS Filed May 1 1942 II 1 "I! m1 30 [In I 9 I -14 J? a o/12 2 Sheets-Sheet l INVENTOR Aug, 24, W43. R. E. SLATER 293273 36 TUBE DRAWING APPARATUS Filed May 1, 1942 2 Sheets-Sheet 2 A gi a a "O 12 15 F j j 1" v 1% I H 29 2 8 II 5| I I mVEAToR jlga ymqrgd ESZCZZ'QF ATTORNEYS Patented Aug. 24,,1943' 'r Bn/nmwmG'Ar-mnaws Raymond E. Slatcr, New Rochelle, N. Y., assignor to Remington Arms Company, Inc., a corporation of Delaware Application May 1, 1942, Serial No. 441,2sc

. 7 Claims. This invention relates to machines for drawticulariy to themeans for stripping the tubes from the punch after they have been passed through a die.

In the drawing of'articlessuch as cartridge cases the'wall must remain straight and not be crumpled or distorted. Work .is performed on the case after it is drawn, such as trimming, tapering, etc., and any damage tothe wall will cause dim'culty- Damage to .the wall, or strain created in the metal, in the-processing of cartridge cases, may extend to a portion of the finished product thereby creating apotential point of failure. This, of course, is not limited to cartridge cases and may be true of any tube. v

As is well known, a tube may be drawn from a hat strip or a. cup by passing the blank through a die by means of a reciprocating punch and the clearance between the die and the punch will govern the final dimensions of the tube. The drawing may take place in one draw, or as many as desired, depending upon the material, size and other factors. The material may be annealed or heat treated between draws as becomes necessary. Cartridge cases are-usually 'ingthin tubes such as cartridge cases and parmade of brass but the invention is applicable to other materials such as zinc, steel, aluminum,

etc. The invention is also applicable to other means of forming such as where the blank is supported on a mandrel and shaped by rolls. The punch may remain stationary and the strip per reciprocated relative thereto.

In one of the previous means of removing ,the drawn case or tube fromthe-punch, the

edge of the caseis allowed to come into contact with-- a surface which restrains the case and then as the punch-returns to its original position the case is removed from the punch.

When this method is used, the exterior wall of the case is unsupported and the wall may be damaged. 'It is necessary that the surface against which the edge of the drawn case contacts in removal from the punch be continuous so as to prevent damage to any localized part of the edge. Such localized damage may result, for ei'rample, if projections were used to strip the same. Some methods of stripping use springpressed projections for the purpose. In addition to the damage which may be done to the edge ofsthe case the projections mayscratch the tube as it passes through and in articles such as cartridge casesthis'is very serious. Scratches on the case from the drawing operation are potentialsources oi? weakness and are liable to result in split cases upon firing It is also desirable to positively contract the stripper so as toinsure removal of the drawntube. This is particularlytrue with automatic machinery wherein the blanks are being constantlyied to'the punch. Failure to remove a drawn case might cause a stoppage of the machine with resultant loss of time and dam- 'age to the machine and material. Strippers which are dependent solely on spring pressure may fail to strip the case.

One of the objects of the inven ion is to strip the, cases from the punch positively and without damage to the edge and wall of the case. Other objects'of the invention will appear from the following description and illustrations which are not intended to limit the use of the invention to the forms shown and described.

In the drawings: I

Fig. 1 is an elevation, partially in section, showing a punch with a case thereon about to be drawn.

Fig. 2 is similar to Fig. 1 with the exception that the case has ;been partially passed through the die.

Fig. 3 is similar to Fig. 1 with the exception that the punch has started on its return movement and the stripper is in positive contracted position to strip the tube from the punch.

Fig. {i is a perspective view of the preferred form of a stripper.

Fig. 5 is a perspective View of another form of stripper.

Fig. 6 is abottom view of the stripper shown inFigs.1to3.

Fig. 'l' is a fragmentary elevational view of the joint between stripper segments taken in the direction l.-i of Fig. 6.

Fig. 8 is a perspective view of a case which has had the edge damaged by means of a stripper which does not support thewall of the case. Fig. 9 is airagmentary sectional view of a I modification oi the Joint between segments.

Fig. 10 is a sectional elevation 01. a die 'in-' corporating part of applicant's invention. -The invention will be. described particularly relative to the drawing of a cartridge case but, as stated previously, it is to be distinctly understood that it may be usedfor other purpcses than the manufacture of cartridge cases. For

- example; there are many tube drawing operations wherein it, isdesired not to damage the a edge of the drawn tube in thie stripping operation. p. p

In Fig. 1, fl is the punch of conventional type which may be reciprocated by means of the usual press commonly used in the art and may be mechanically or hydraulically operated. II is the die holding block which is positioned in the table of the punch press in proper alignment with the punch. l2 represents a drawing die of conventional type. able, the the die holder may be made of sufiicient height so that a plurality of drawing dies may be used, placed one upon the other. The diameter of the throat l3 of the drawing die may be made substantially that of the desired diameter of the tube to be drawn. v

A stripper sleeve M is placed in the bottom of the die holder II and a plate l5 having a hole I6 is placed over the top of the die holder so as to hold the dies and stripper sleeve in position. The die holder, dies, and plate l5 are merely exemplary and may or may not be integral parts of the machine. The stripper sleeve M has a conical bore 3| for the purpose which will be described presently. There is a hole IT in the bottom of the die holder to allow the passage of the drawn case therethrough.

The form of the stripper shown in Fig. 1 comprises three segments l8, as shown in Figs. 4 and 6. A smaller or greater number of segments may be used. These are held together by means of the springs l9 and located in the grooves 2| and 22, respectively. The springs shown are coil springs which are joined together. It is evident, however, that other types of yieldable elements, such as rubber bands,- or that a single spring or yieldable element may be used as shown in Fig. 6.

Figs. 1, 4 and 6. a bore 23 having two diameters 24 and 25 joined by a stripper shoulder 26, passes therethrough. The stripper normally rests in the bottom of the die holder as shown in Fig. 1.

As the punch |0 carries the tube 21 through the die, it will pass through the bore 23. Because the diameter 24 is substantially that of the punch the outside wall of the case will force the segments apart against the pressure of the yieldable means l9 and 20 so that the case or punch may pass therethrough. as shown in Fig. 2. After the punch and tube pass completely through the die, and far enough so that the upper edge 28 has passed below the stripper shoulder 26, the

stripper will move together so that the bore with.

the diameter substantially the same as the diameter of the drawn case will completely encircle the same. This will enclose the'upper edge and wallet the case between the stripper assembly and the punch. The portion of the bore having the diameter 24 will encircle the punch and then as th punch reverses and moves upwardly, the stripper assembly will be carried upwardly in the stripper sleeve H. The conical bore 3| of the stripper sleeve'willcoact with the mating conical surface of the exterior surface 29 of the exterior of the assembled stripper segments. This coaction will positively hold the stripper segments in their contracted relationship as the punch continues its upward movement and strips the case from the punch. -It is seen, therefore, that the stripper is positively held in closed position and support the upper edge of the case between the stripper and the punch so as to prevent crumpling ordamage thereto. The continuous stripper shoulder 26 also insures that no localized It is to be understood, if desir-' damage will be done to the edge. A stripper made in accordance with the invention will prevent damage to the upper edge of the case, which is particularly necessary for thin tubes. If desirable, the various mating edges of the grooves may be rounded as shown in Fig. '7 so as to eliminate any sharp corners.

The entrance portion of the bore 23 may be rounded so as to assist in properly centering the stripper.

As shown in Fig. 9 the surface under the springs at the joints 'may be relieved as at 32 so as to assist in prevention of damage to the springs or yieldable elements.

A further modification of the invention is shown in Fig. 10 wherein 33 is the die with throat 34 and tube'supporting bore 35. The tubewill be caught on the stripping shoulder 36 on return movement of the punch. The diameter of bore 35 is uch that the edge of the tube will be closely supported against the punch so as to prevent crumpling.

In the forms of Figs. 1 to 4, and 6, two springs or yieldable elements are shown for'holding the stripper in it assembled relationship. The advantage of such a construction is that there are springs located relative to each of the two diameters of the bore through the stripper.

It is evident from the foregoing description that a superior device has been evolved for the removal of tubes in forming operations. The invention is not to be limited to the details shown herein, described in the drawings and illustrated, but is to be construed broadly as covering all equivalent devices falling within the scope of the appended claims.

What is claimed is:

1. In a means for stripping a walled article from a punch; continuous means to engage the end of the article; and means to substantially completely support the outer Wall of the article adjacent said continuous means in conjunction with said punch with sufiicient force to prevent 'crumpling of the wall of said article as the article is stripped from the punch.

2. In a tube drawing device, a punch; a die; means to strip a tube from the punch comprising a yieldable contractible segmental stripper through which the punch and drawn tube passes,

said segments having a substantially continuous shoulder to engage the edge of the drawn tube after it is passed therethrough; and means adjacent the shoulder to support the outer wall of said tube between the punch and the segments with suflicient force to prevent crumpling of said wall as the article is stripped from the punch.

3. In a cartridge case drawing device including 1 a reciprocating punch and a die; a yieldable contractible segmental stripper assembly through which the punch and drawn case passes, said segments defining a bore of two diameters, one of which is subtantially the same as the punch and the other of which is substantially the diameter of the drawn case whereby the wall of. said. case is supported between the punch and the.

ping shoulder, the bore remote from the die being substantially the diameter 01' the drawn tube and the other bore being smaller, the wall of said tube adjacent the shoulder being held between the punch and-greater diameter bore with suflicient force to prevent crumpling. of said wall, and means to yieldably holdsaid segments in assembled relationship. t

5. In a thin tube drawing apparatus including a reciprocating punch and a die; means for stripping a thin tube from the punch after it has been dra n through the die comprising segments defining bores of two diameters joined by a stripping shoulder, the bore remote from the die being substantially the diameter of the drawn tube and the. other bore being substantially the diameter of the punch, the wall of said tube adjacent the shoulder being held between the punch and greater diameter bore with sufficient force to prevent crumpling of said wall; means to yieldably hold said segments, in contracted assembled relationship; and means to positively contract said segments as the punch starts on its return reciprocation after passing through the yieldably held segments with a drawn tube.

6. In a thin tube drawing apparatus including areciprocating punch and 'a-die; means for stripping a thin tube from the punch after it has been drawn through the die comprising segments defining bores of two diameters joined by a stripping shoulder, the bore remote from the die being, substantially the diameter of the drawn tube and the other bore being substantially the diameter of the punch, the wall of said tube adjacent the shoulder being held between the punch and greater diameter bore with suflicient force to prevent crumpling of said wall; means to yieldably hold said segments in contracted assembled relationship, the, exterior surface of said contracted assembled segments being in the form 01 atmcated cone; and guide means having a bore the shape of said truncated cone coacting with said segments and allowing relative longitudinal movement between the assembled segments and the guide means, so as .to positively contract the segments as the punch starts on its return reciprocation after passing through the yieldably held segments with a drawn tube.

'7. In a thin tube drawing apparatus including a reciprocating punch and a die; means for stripping a thin tube from the punch after it has been drawn through the die comprising segments defining bores of two diameters joined by a stripping shoulder, the bore remote from the die being substantially the diameter of the drawn tube and the other bore being substantially the diameter of thepunch, the wall of said tube adjacent the shoulder being held between the punch and greater diameter bore with sumcient force to prev vent crumpling of said wall, said assembled. segmentghaving an exterior surface in the form of a truncated cone withtwo grooves therein; 

